• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.193-194
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• 2012

그래핀(graphene)은 탄소원자가 육각형 벌집 모양 배열의 격자구조를 가지는 원자 한층 두께의 이차원 물질이다. 그래핀은 전도띠(conduction band)와 가전자띠(valence band)가 한 점에서 만나고 에너지와 역격자의 k 벡터가 선형적으로 비례하는 에너지 구조를 가진다. 이로 인해 그래핀은 매우 빠른 전하 이동도를 가지며 원자 한 층의 두께임에도 불구하고 약 2.3%의 빛을 흡수할 수 있으며 자외선 영역부터 적외선 영역까지의 넓은 파장대의 빛을 흡수 할 수 있다. 이와 같은 그래핀의 우월한 성질을 이용하면 광 응답에 고속으로 반응하고 높은 주파수의 광통신에서도 작동 할 수 있는 그래핀 광소자를 제작할 수 있게 된다. 하지만 미래의 고속 그래핀 광소자를 실현하기에 앞서 그래핀의 광응답에 대한 정확한 이해가 필요하다. 그리하여 본 연구에서는 그래핀 광소자를 제작하고 광소자의 광응답 전기적 성질을 분석하여 그래핀의 광응답 특성을 얻어내고자 실험을 진행하였다. 그래핀을 채널 물질로 하고 소스, 드레인, 후면 게이트를 가지는 일반적인 그래핀 전계효과 트랜지스터(field-effect transistor)를 제작하고 채널에 빛을 비추고 비추지 않은 상태에서의 전기적 성질을 측정하고 그 때 얻어진 그래프의 광응답의 원인을 조사하였다. 이 때 얻어지는 $I_D-V_G$ 그래프가 광 조사 시 왼쪽으로 이동하게 되는데 이의 원인을 각 게이트 전압 구간별로 $I_D$-t 그래프를 획득하여 분석하였다. 또한 광원에 펄스를 인가하여 펄스 형태의 광원을 그래핀 전계효과 트랜지스터에 조사시키고 이에 따른 전기적 성질 변화를 관찰하였다 이 때 다양한 게이트 전압이 인가된 상태에서 레이저 펄스 광원에 의한 광전류를 검출하였으며 이를 분석하였다.

• Journal of Software Assessment and Valuation
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• v.16 no.2
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• pp.135-142
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• 2020

In this paper, we describe the iris localization method in RGB images. Most of the iris localization methods are developed for infrared images, thus an iris localization method in RGB images is required for various applications. The proposed method consists of four stages: i) detection of the candidate irises using circular Hough transform (CHT) from an input image, ii) detection of a pupil center based on deep learning, iii) determine the iris using the pupil center, and iv) correction of the iris region. The candidate irises are detected in the order of the number of intersections of the center point candidates after generating the Hough space, and the iris in the candidates is determined based on the detected pupil center. Also, the error due to distortion of the iris shape is corrected by finding a new boundary point based on the detected iris center. In experiments, the proposed method has an improved accuracy about 27.4% compared to the CHT method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.7
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• pp.1653-1660
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• 2010

In this study, change of body surface temperature was measured using Digital Infrared Thermographic Imaging(DITI) to check muscle fatigue recovery & muscle pain control by magnetic stimulations. For clinical trials, subjects were divided into 3 groups : non stimulation group(NSG), electrical stimulation group(ESG) and micro magnetic stimulation group(MSG). In result, temperature differences between left and right arm surfaces were measured as much as $0.86{\pm}0.43^{\circ}C$(n=96) after the exercise, $0.78{\pm}0.12^{\circ}C$ after the electrical stimulation and $0.1{\pm}0.39^{\circ}C$ after the micro magnetic stimulation. Also after 3days, temperature differences between left and right arm surfaces were measured as much as $0.3{\pm}0.14^{\circ}C$ in the NSG, $0.05{\pm}0.21^{\circ}C$ in the ESG and $0.03{\pm}0.21^{\circ}C$ in the MSG. These data showed that the lowest temperature difference between left/right body surface was measured in MSG.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.78-86
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• 2017

Japan has a lot of interest about weapons systems development of surrounding national and has invested heavily in securing intelligence assets to get information about them, because of conflict issues between Japan and Russia with four northern islands, China with Senkaku Islands and entry policy into the Pacific. Japan has used a large budget to detect and intercept ballistic missile for reasons of the launch of the Taepodong missile in 1998. After took over SIGINT equipments which U.S. force had operated in 1950s~1960s, Japan made a technological analysis and advanced IT technology to produce superior equipments. Japan's SDF has installed them in 19 locations across Japan. In addition, Japan's JASDF has installed advanced early warning RADAR to detect aircraft and high speed ballistic missile entering JADIZ with S-band in 28 locations across Japan. It is possible to detect missile launch preparations, engine tests, and launch moments at any time for operation of 6 satellites high resolution reconnaissance system and 6 aegis ships. In close cooperation with the US, Japan is accessible to the SBIRS networks which detects the launch of a ballistic missile in neighboring countries. In the future, Because the United States wants Japan to act as part of the United States in East, south Asia, it is believed that the exchange of intelligence on the surrounding countries between two countries will be enhanced.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.3
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• pp.249-255
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• 2017

The finger vein recognition technology is a method to acquire a finger vein image by illuminating infrared light to the finger and to authenticate a person through processes such as feature extraction and matching. In order to recognize a finger vein, a 2D mask-based two-dimensional convolution method can be used to detect a finger edge but it takes too much computation time when it is applied to a low cost micro-processor or micro-controller. To solve this problem and improve the recognition rate, this study proposed an extraction method for the region of interest based on virtual core points and moving average filtering based on the threshold and absolute value of difference between pixels without using 2D convolution and 2D masks. To evaluate the performance of the proposed method, 600 finger vein images were used to compare the edge extraction speed and accuracy of ROI extraction between the proposed method and existing methods. The comparison result showed that a processing speed of the proposed method was at least twice faster than those of the existing methods and the accuracy of ROI extraction was 6% higher than those of the existing methods. From the results, the proposed method is expected to have high processing speed and high recognition rate when it is applied to inexpensive microprocessors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4A
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• pp.239-249
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• 2012

Recently, the virtual view generation method using depth data is employed to support the advanced stereoscopic and auto-stereoscopic displays. Although depth data is invisible to user at 3D video rendering, its accuracy is very important since it determines the quality of generated virtual view image. Many works are related to such depth enhancement exploiting a time-of-flight (TOF) camera. In this paper, we propose a fast 3D scene capturing system using one TOF camera at center and two high-resolution cameras at both sides. Since we need two depth data for both color cameras, we obtain two views' depth data from the center using the 3D warping technique. Holes in warped depth maps are filled by referring to the surrounded background depth values. In order to reduce mismatches of object boundaries between the depth and color images, we used the joint bilateral filter on the warped depth data. Finally, using two color images and depth maps, we generated 10 additional intermediate images. To realize fast capturing system, we implemented the proposed system using multi-threading technique. Experimental results show that the proposed capturing system captured two viewpoints' color and depth videos in real-time and generated 10 additional views at 7 fps.

• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.54-59
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• 2008

We report on the measurements of absorption spectra from acetylene ($^{12}C_2H_2$) and hydrogen cyanide ($H^{13}C^{14}N$) for wavelength reference in the C-band (conventional band) region using a supercontinuum optical source generated from a mode-locked $Cr^{4+}$:YAG laser. The center wavelength of the mode-locked $Cr^{4+}$:YAG laser was 1510 nm and the pulse duration was 75 fs at 100 MHz repetition rate. The supercontinuum source achieved a flatness of ${\pm}5dB$ over a wavelength range of more than 400 nm, using a 20 m long photonic crystal fiber. The measured absorption spectra from acetylene ($^{12}C_2H_2$) and hydrogen cyanide ($H^{13}C^{14}N$) had more than 50 lines and were analyzed for wavelength standardization.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.2
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• pp.379-385
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• 2017

In general, distribution board, panel board and motor control center can be installed over a wide area such as residence of group, building, schools, factories, ports, airports, water service and sewerage, substation and heavy industries that are used to supply converts the voltages extra high voltage into optimal voltage. There are electrical accidents due to rise of contact temperature, loose contact between busbar, deterioration of the contact resistance, over temperature of the busbars. In this paper, we designed and implemented the busbar joint and temperature measurement system, which can measure the joint resistance of busbar and loose connection between busbar using potentiometer and non-contact infrared sensor. The experimental results show that tightening the bolt and nut is fully engaged, resistance was decreased and maximum error range was 0.1mm. Also, the experimental result showed that the temperature at the contact area is increased from $27.3^{\circ}C$ to $69.3^{\circ}C$by the contact resistance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.581-584
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• 2009

Recently, the cameras which used for observation are installed in children protection area and local crime prevention area in order to protect life and property and by its work being recognized and are installed more. Normal cameras have cost problem to observe multiple area and detail, because they can observe only one place. PTZ camera can observe multiple area by moving focus by schedule or remote control, but it can't automatically move the focus of it to the place where event occurred, because it can't recognize the place. In this study, we can monitor multiple area effectively, by installing a wireless sensor node equipped with temperature, lighting, gas and human detection sensor to each area, to monitor many place low-price and actively and to move the focus of PTZ camera to preset position, and send recorded video to the user, when the various sensor data received from wireless sensors in observation area are to be determined abnormal by analyzing. In addition, at night we can record a scene using infrared, but to reduce power consumption of lighting system which are installed to improve resolution, it supplies power to the lighting system when event occurred. So we were able to implement low power green monitoring system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.224-226
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• 2016

With the technical development and rapid increase of private demand, the new market for unmanned vehicle combined with the characteristics of 'unmanned automation' and 'vehicle' is rapidly growing. Even though the pilot driving is currently allowed in some countries, there is no country that has institutionalized the formal driving of self-driving cars. In case of the existing vehicles, safety incidents are frequently happening due to the frequent malfunction of the rear sensor, blind spot of the rear camera, or drivers' carelessness. Once such minor flaws are complemented, the relevant regulations for the commercialization of self-driving car and small drone could be relieved. Contrary to the ultrasonic and laser sensors used for the existing vehicles, this paper aims to attempt the distance measurement by using the depth sensor. A depth camera calculates the distance data based on the TOF method calculating the time difference by lighting laser or infrared light onto an object or area and then receiving the beam coming back. As this camera can obtain the depth data in the pixel unit of CCD camera, it can be used for collecting depth data in real-time. This paper suggests to solve problems mentioned above by using depth data in real-time and also to design the obstacle avoidance system through distance measurement.